[trainer] move secondary methods into a separate file (#10363)

* move secondary methods into a separate file

* cleanup

* style

src/transformers/trainer.py

@@ -19,7 +19,6 @@ The Trainer class, to easily train a 🤗 Transformers from scratch or finetune
 import collections
 import gc
 import inspect
-import json
 import math
 import os
 import re
@@ -82,7 +81,6 @@ from .trainer_pt_utils import (
     SequentialDistributedSampler,
     distributed_broadcast_scalars,
     distributed_concat,
-    get_learning_rate,
     nested_concat,
     nested_detach,
     nested_numpify,
@@ -226,6 +224,8 @@ class Trainer:
 
     """
 
+    from .trainer_pt_utils import _get_learning_rate, log_metrics, metrics_format, save_metrics
+
     def __init__(
         self,
         model: Union[PreTrainedModel, torch.nn.Module] = None,
@@ -1130,7 +1130,7 @@ class Trainer:
             tr_loss -= tr_loss
 
             logs["loss"] = round(tr_loss_scalar / (self.state.global_step - self._globalstep_last_logged), 4)
-            logs["learning_rate"] = get_learning_rate(self)
+            logs["learning_rate"] = self._get_learning_rate()
 
             self._total_loss_scalar += tr_loss_scalar
             self._globalstep_last_logged = self.state.global_step
@@ -1345,61 +1345,6 @@ class Trainer:
         self.state.log_history.append(output)
         self.control = self.callback_handler.on_log(self.args, self.state, self.control, logs)
 
-    def metrics_format(self, metrics: Dict[str, float]) -> Dict[str, float]:
-        """
-        Reformat Trainer metrics values to a human-readable format
-
-        Args:
-            metrics (:obj:`Dict[str, float]`):
-                The metrics returned from train/evaluate/predict
-
-        Returns:
-            metrics (:obj:`Dict[str, float]`): The reformatted metrics
-        """
-
-        metrics_copy = metrics.copy()
-        for k, v in metrics_copy.items():
-            if "_mem_" in k:
-                metrics_copy[k] = f"{ v >> 20 }MB"
-            elif k == "total_flos":
-                metrics_copy[k] = f"{ int(v) >> 30 }GF"
-            elif type(metrics_copy[k]) == float:
-                metrics_copy[k] = round(v, 4)
-
-        return metrics_copy
-
-    def log_metrics(self, split, metrics):
-        """
-        Log metrics in a specially formatted way
-
-        Args:
-            split (:obj:`str`):
-                Mode/split name: one of ``train``, ``eval``, ``test``
-            metrics (:obj:`Dict[str, float]`):
-                The metrics returned from train/evaluate/predictmetrics: metrics dict
-        """
-
-        logger.info(f"***** {split} metrics *****")
-        metrics_formatted = self.metrics_format(metrics)
-        k_width = max(len(str(x)) for x in metrics_formatted.keys())
-        v_width = max(len(str(x)) for x in metrics_formatted.values())
-        for key in sorted(metrics_formatted.keys()):
-            logger.info(f"  {key: <{k_width}} = {metrics_formatted[key]:>{v_width}}")
-
-    def save_metrics(self, split, metrics):
-        """
-        Save metrics into a json file for that split, e.g. ``train_results.json``.
-
-        Args:
-            split (:obj:`str`):
-                Mode/split name: one of ``train``, ``eval``, ``test``, ``all``
-            metrics (:obj:`Dict[str, float]`):
-                The metrics returned from train/evaluate/predict
-        """
-        path = os.path.join(self.args.output_dir, f"{split}_results.json")
-        with open(path, "w") as f:
-            json.dump(metrics, f, indent=4, sort_keys=True)
-
     def _prepare_inputs(self, inputs: Dict[str, Union[torch.Tensor, Any]]) -> Dict[str, Union[torch.Tensor, Any]]:
         """
         Prepare :obj:`inputs` before feeding them to the model, converting them to tensors if they are not already and

src/transformers/trainer_pt_utils.py

@@ -16,11 +16,13 @@
 Torch utilities for the Trainer class.
 """
 
+import json
 import math
+import os
 import warnings
 from contextlib import contextmanager
 from dataclasses import dataclass
-from typing import Iterator, List, Optional, Union
+from typing import Dict, Iterator, List, Optional, Union
 
 import numpy as np
 import torch
@@ -263,29 +265,6 @@ def _get_first_shape(arrays):
     return arrays.shape
 
 
-def get_learning_rate(trainer):
-    if trainer.deepspeed:
-        # with deepspeed's fp16 and dynamic loss scale enabled the optimizer/scheduler steps may
-        # not run for the first few dozen steps while loss scale is too large, and thus during
-        # that time `get_last_lr` will fail if called during that warm up stage, so work around it:
-        try:
-            last_lr = trainer.lr_scheduler.get_last_lr()[0]
-        except AssertionError as e:
-            if "need to call step" in str(e):
-                logger.warn("tried to get lr value before scheduler/optimizer started stepping, returning lr=0")
-                last_lr = 0
-            else:
-                raise
-    else:
-        last_lr = (
-            # backward compatibility for pytorch schedulers
-            trainer.lr_scheduler.get_last_lr()[0]
-            if version.parse(torch.__version__) >= version.parse("1.4")
-            else trainer.lr_scheduler.get_lr()[0]
-        )
-    return last_lr
-
-
 class DistributedTensorGatherer:
     """
     A class responsible for properly gathering tensors (or nested list/tuple of tensors) on the CPU by chunks.
@@ -563,3 +542,88 @@ class DistributedLengthGroupedSampler(DistributedSampler):
         assert len(indices) == self.num_samples
 
         return iter(indices)
+
+
+# In order to keep `trainer.py` compact and easy to understand, place any secondary PT Trainer
+# helper methods here
+
+
+def _get_learning_rate(self):
+    if self.deepspeed:
+        # with deepspeed's fp16 and dynamic loss scale enabled the optimizer/scheduler steps may
+        # not run for the first few dozen steps while loss scale is too large, and thus during
+        # that time `get_last_lr` will fail if called during that warm up stage, so work around it:
+        try:
+            last_lr = self.lr_scheduler.get_last_lr()[0]
+        except AssertionError as e:
+            if "need to call step" in str(e):
+                logger.warn("tried to get lr value before scheduler/optimizer started stepping, returning lr=0")
+                last_lr = 0
+            else:
+                raise
+    else:
+        last_lr = (
+            # backward compatibility for pytorch schedulers
+            self.lr_scheduler.get_last_lr()[0]
+            if version.parse(torch.__version__) >= version.parse("1.4")
+            else self.lr_scheduler.get_lr()[0]
+        )
+    return last_lr
+
+
+def metrics_format(self, metrics: Dict[str, float]) -> Dict[str, float]:
+    """
+    Reformat Trainer metrics values to a human-readable format
+
+    Args:
+        metrics (:obj:`Dict[str, float]`):
+            The metrics returned from train/evaluate/predict
+
+    Returns:
+        metrics (:obj:`Dict[str, float]`): The reformatted metrics
+    """
+
+    metrics_copy = metrics.copy()
+    for k, v in metrics_copy.items():
+        if "_mem_" in k:
+            metrics_copy[k] = f"{ v >> 20 }MB"
+        elif k == "total_flos":
+            metrics_copy[k] = f"{ int(v) >> 30 }GF"
+        elif type(metrics_copy[k]) == float:
+            metrics_copy[k] = round(v, 4)
+
+    return metrics_copy
+
+
+def log_metrics(self, split, metrics):
+    """
+    Log metrics in a specially formatted way
+
+    Args:
+        split (:obj:`str`):
+            Mode/split name: one of ``train``, ``eval``, ``test``
+        metrics (:obj:`Dict[str, float]`):
+            The metrics returned from train/evaluate/predictmetrics: metrics dict
+    """
+
+    logger.info(f"***** {split} metrics *****")
+    metrics_formatted = self.metrics_format(metrics)
+    k_width = max(len(str(x)) for x in metrics_formatted.keys())
+    v_width = max(len(str(x)) for x in metrics_formatted.values())
+    for key in sorted(metrics_formatted.keys()):
+        logger.info(f"  {key: <{k_width}} = {metrics_formatted[key]:>{v_width}}")
+
+
+def save_metrics(self, split, metrics):
+    """
+    Save metrics into a json file for that split, e.g. ``train_results.json``.
+
+    Args:
+        split (:obj:`str`):
+            Mode/split name: one of ``train``, ``eval``, ``test``, ``all``
+        metrics (:obj:`Dict[str, float]`):
+            The metrics returned from train/evaluate/predict
+    """
+    path = os.path.join(self.args.output_dir, f"{split}_results.json")
+    with open(path, "w") as f:
+        json.dump(metrics, f, indent=4, sort_keys=True)